Syntheses, optical properties, and bioimaging application of near-infrared aza-BODIPY dyes with electronic push-pull system

It is still a challenging work of developing near-infrared (NIR) fluorescence dyes with excellent optical properties. Herein, we synthesized a series of NIR aza-BODIPY fluorescence dyes with electronic push-pull system and further investigated their photophysical properties, photostability, and application in cellular imaging. It was found that introducing electron-withdrawing groups (EWGs) on the para-position of aza-BODIPY 1,7-phenyls not only leads to the significant redshift of absorption and fluorescence emission bands of aza-BODIPY dyes but also increases their fluorescence quantum yield and photostablility. The DFT calculations and cyclic voltammetry measurements proved that introducing EWGs on para-position of 1,7-phenyls can decrease the energy level difference between HOMO and LUMO, resulting in the redshift of maximum absorption and emission wavelengths. On the basis of the feasible experiment results of cellular imaging and cytotoxicity assay, it is expected that the optimized aza-BODIPY dyes have a bright application prospect for in vivo cellular or tissue imaging.